Doug, do you happen to know what the upper and lower vertical separation refer to.. ie. 1 is less separation than 2 but does it relate to 1 layer in height or what?
Read the text prompt for the fields, the tooltip text, and the description of the fields in this thread: viewtopic.php?f=8&t=2135
All three say "layers".....so it must be layers!
And the answer to your follow-up question, where support crosses profile boundaries, the top and bottom gap settings are ignored at the profile boundaries!....just like the number of top and bottom layers are ignored at the profile boundary.